An easy, fast, and accurate way to add device detection is via WURFL InFuze for Varnish. Not free, but it works.
https://www.scientiamobile.com/page/wurfl-infuze

My traffic is 60% mobile 35% desktop 5% tablet. so Varnish without device detection is useless

yes please add this as a feature to the current Varnish cache settings page to allow for device detection and separate caching for each devices that is configured.

For example:Our sites have phone specific content that is different from tablet and desktop(usability purpose). So we would need varnish cache to detect phone and create a cached version for them and also create a standard cache for all other devices.

These links should give you the basic of how to setup varnish cache for different devices based on user agent:
https://www.varnish-cache.org/docs/trunk/users-guide/devicedetection.html
https://github.com/varnishcache/varnish-devicedetect
https://spin.atomicobject.com/2013/02/11/varnish-cache-mobile-devices/

Yes, please! On WordPress with WP Touch, we can't enable Varnish because it'll just create one "bucket" of cached pages.

Ideally, Varnish would create separate versions for desktop & mobile browsers...but barring that, if we could exclude by user agent, we could at least still cache desktop pages.

https://support.wptouch.com/support/solutions/articles/5000537668-configuring-cache-plugins-for-wptouch

Hi,
Majority of our customers are using other devices than laptops and desktop computers.
If our online shop which we use to sell our products and services does not function on android phones, etc. what is the point of using Varnish!? Please consider this urgently, otherwise I really have to find another company to host my website!
Thank you very much in advance for taking care of the matter.
Best regards,

Varnish without mobile detection - is really of no value - seeing that currently more visitors are coming from mobile than desktop and we have no way of diferenciating between them and sending to correct page. This is an urgent requirement

Leonard